These studies are designed to elucidate the mechanisms by which stress affects reproductive performance and produces abnormalities of fetal and postnatal development in the rat. Specifically the proposed studies will consider: (1) the effect of stress during the preimplantation stage and during early, middle and late post-nidation gestation on pituitary LH and prolactin and ovarian progesterone and estrogen secretion; (2) the effect of these stress treatments in hormonal pregnancy support systems will be correlated with the effect of the stressors on pregnancy outcomes, the numbers and normalcy of fetuses born; (3) whether stress interferes with reproduction by decreasing blood flow to the uterus or to the pituitary and ovaries; (4) the normalcy of postnatal development of neuroendocrine reproductive control mechanisms in offspring born from mothers receiving measured stress during pregnancy. Studies of the physiology of stress in rats will provide insight and guidance into related problems of the effect of stress on human function, including human reproduction.